Fix file imports

Author: aeisenberg

extensions/ql-vscode/src/quick-query.ts

@@ -11,10 +11,8 @@ import {
   getInitialQueryContents,
   getPrimaryDbscheme,
   getQlPackForDbscheme,
-  ProgressCallback,
   showAndLogErrorMessage,
   showBinaryChoiceDialog,
-  UserCancellationException
 } from './helpers';
 
 const QUICK_QUERIES_DIR_NAME = 'quick-queries';